The present invention relates to an improved looping mechanism used to facilitate stitching in buttonhole sewing machines. Specifically, this invention allows the looping needles to engage the thread of the main needle which is passed through a garment in which a buttonhole is to be formed.
Sewing machines repeatedly stitch and shift fabric through an intricate sequence of movements. To make a stitch, the sewing machine moves a main needle up and down through the cloth, carrying thread with it. As the main needle comes up from the bottom of its stroke, a looper needle catches and secures the thread, creating a loop. When the main needle descends again, the main needle enters the thread loop, and the loop starts to slide off the looper needle. As the main needle continues to descend, the thread loop slides off the looper needle and is drawn up on the succeeding stroke. Two looper needles are used so that one can reset while the other is creating a loop in the thread.
Needs exist for a reliable, simplified looper apparatus and methods for promoting long lasting error free sewing machines.